Fumitremorgin B (2), isolated from Aspergillus fumigatus together with fumitremorgin A (1), caused severe tremors and convulsion in experimental animals. The structure of fumitremorgin B was determined from the spectral data. The stereochemistry, including the absolute configuration, was determined by X-ray analysis and comparison of the ORD of proline obtained from this compound with that of authentic L-(-)-proline.
